This invention relates to apparatus for assembling a core for receiving wound sheet material.
Cores for receiving wound sheet material are well known. The cores are extensively used in the paper industry for receiving wound sheet material in the form of paper, plastics material or thin cardboard. Reels formed of the core and the wound sheet material are then used in printing works where the wound sheet material is printed, for example for purposes of producing newspapers, packaging or wrapping.
For the winding of the sheet material on the cores, it is essential that the cores are accurately produced in length. Small variations in core lengths have a cumulative effect when the cores are mounted end to end. If a plurality of cores are mounted end to end and wound with a single width of sheet material, then the sheet material has to be cut such that the cuts coincide exactly with the ends of each core. If the cuts do not coincide exactly with the ends of each core, then the wound sheet material can overlap two adjacent cores. The two adjacent cores then cannot be separated from each other because the overlaying sheet material holds the cores together.
The cores traditionally comprise a tube, a first end member inserted in a first end of the tube, and a second end member inserted in a second end of the tube. If the first and the second end members are not fully inserted into their tubes then the core will be of a length which is incorrect to start with. Also, the core will be of a length which will vary during use. For example, any axial pressure applied to a first or a second end member not fully inserted into its end of the tube would result in the first or the second end member moving slightly, with a subsequent variation in the overall length of the core. Reels comprising a core and wound sheet material are large and they are held in place during printing or other works by chucks which exert considerable axial pressure. Even if the first and the second end members are fastened in their ends of the tube by fasteners such for example as screws, the first and the second end members may still get pushed in axially by the considerable axial forces exerted from the holding chucks.